Lowest temperature recorded on Earth

Aerial photograph of Vostok Station, the coldest directly observed location on Earth.

The lowest natural temperature ever directly recorded at ground level on Earth is −89.2 °C (−128.6 °F; 184.0 K), which was at the Soviet Vostok Station in Antarctica, on July 21, 1983. Analysis of satellite data indicated a probable temperature of around −93.2 °C (−135.8 °F; 180.0 K), also in Antarctica, on August 10, 2010; however, this reading was not confirmed by ground measurements.

A 2009 study estimated that under exceptional climate conditions similar to those recorded at Vostok in 1983, temperatures higher on the plateau around Dome Argus could potentially drop as low as −95 °C (−139 °F; 178 K). On August 10, 2010, Landsat 8 observations measured a surface temperature of −93.2 °C (−135.8 °F; 180.0 K) at 81.8°S 59.3°E, along a ridge between Dome Argus and Dome Fuji, at 3,900 m elevation. The result was reported at the 46th annual meeting of the American Geophysical Union in San Francisco, in December 2013; it is a provisional figure, and may be subject to revision.

The value may not be listed as the record coldest temperature as it was measured by remote sensing satellites and not by ground-based thermometers, unlike the 1983 record. The temperature announced reflects that of the ice surface, while the Vostok readings measured the air above the ice, and so the two are not directly comparable; however, it is clear that the real temperature at the site is lower than that recorded at Vostok in 1983.

Historical progression

On January 21, 1838 a recording was made by the Russian merchant Neverov in Yakutsk, of −60 °C (−76 °F; 213 K). On January 15, 1885 H. Wild reported that a temperature of −68 °C (−90 °F; 205 K) was noted in Verkhoyansk. A later measurement at the same place in February 1892 was reported as −69.8 °C (−93.6 °F; 203.3 K). Soviet researchers later announced a recording of −67.7 °C (−89.9 °F; 205.5 K) in February 1933 at Oymyakon, about 400 miles (640 km) to the south-east of Verkhoyansk; this measurement was reported by Soviet texts through the 1940s as a record low, with the previous measurement from Verkhoyansk retroactively adjusted to −67.6 °C (−89.7 °F; 205.6 K).

The next reliable measurement was made during the 1957 season at the Amundsen–Scott South Pole Station in Antarctica, yielding −73.6 °C (−100.5 °F; 199.6 K) on May 11 and −74.5 °C (−102.1 °F; 198.7 K) on September 17. A subsequent measurement of −88.3 °C (−126.9 °F; 184.8 K), on August 24, 1960, held the record until a temperature of −89.2 °C (−128.6 °F; 184.0 K) was measured at the Soviet Vostok Station, on the Antarctic Plateau, on July 21, 1983. This remains the record for a directly recorded temperature.

Laboratory cooling

Early

In 1904 Dutch scientist Heike Kamerlingh Onnes created a special lab in Leiden with the aim of producing liquid helium. In 1908 he managed to lower the temperature to less than four degrees above absolute zero, to less than −269 °C (4 Kelvin). Only in this exceptionally cold state will helium liquify, the boiling point of helium being at −268.94 °C. Kamerlingh Onnes received a Nobel Prize for his achievement.

Onnes' method relied upon depressurising the subject gases, causing them to cool. This follows from the first law of thermodynamics;

$\Delta U = \Delta Q - \Delta W$

where U = internal energy, Q = heat added to the system, W = work done by the system.

Consider a gas in a box of set volume. If the pressure in the box is higher than atmospheric pressure, then upon opening the box our gas will do work on the surrounding atmosphere to expand. As this expansion is adiabatic and the gas has done work

$\Delta Q = 0$

$\Delta W > 0$

$\Rightarrow \Delta U < 0$

Now as the internal energy has decreased so has the temperature.

Modern

As of November 2000, nuclear spin temperatures below 100 pK were reported for an experiment at the Aalto University's Low Temperature Lab. However, this was the temperature of one particular type of motion—a quantum property called nuclear spin—not the overall average thermodynamic temperature for all possible degrees of freedom. At such low temperatures, the concept of "temperature" becomes multifaceted since molecular motion cannot be assumed to average out across degrees of freedom. The corresponding peak emission will be in radio waves, rather than in the familiar infrared, so it is very inefficiently absorbed by neighboring atoms, making it difficult to reach thermal equilibrium.

In laboratories, a record low temperature of 100 pK, or 1.0 × 10⁻¹⁰ K was recorded in 1999.

The current apparatus for achieving low temperatures has two stages. The first utilizes a helium dilution refrigerator to get to temperatures of millikelvins, then the next stage uses adiabatic nuclear demagnetisation to reach picokelvins.

See also

• Absolute zero
• Timeline of low-temperature technology
• Dilution refrigerator
• Adiabatic demagnetization
• List of weather records#Lowest temperatures ever recorded
• Highest temperature recorded on Earth
• List of weather records#Highest temperatures ever recorded
• Orders of magnitude (temperature)

External links

• Details of HUT experiment, including details of the cryostat